Taking a break from practicing for a holiday dance performance to accompany her friend Davy to the beach, Maryellen finds a barnacle-encrusted ring buried in the sand that looks like lost treasure and is desperately sought by a group of strangers.
Volunteering at the Brooklyn Botanic Garden in the early 1900s, Jewish cousins Rebecca and Ana must find the real culprit when they are unfairly blamed for a series of mishaps in the Japanese garden.
When Rebecca attends summer camp in the country because of the spreading polio epidemic in New York City, she is troubled by a bully in her tent and another fellow camper who is strangely secretive.
When Rebecca helps her injured neighbor, Mr. Rossi, by caring for his pigeons, she discovers a strange black pigeon with an eerie message warning Mr. Rossi of danger, and consults a fortune teller to learn if she is in danger, as well.